of the Fishery Board for Scotland. 



95 



The relation of the free ovarian fluid to the processes of maturation 

 is discussed later (p. 118). 



The Ovarian Devet.opment of the Eggb. 



As previously stated, I have investigated the ovarian development and 

 maturation of the eggs of a number of Teleosteans, belonging for the most 

 part to the group in which the mature egg is pelagic. The investigation 

 was made partly on fresh ovaries examined in ovarian succus or in weak 

 salt solutions, much being learned by graduated compression of the eggs; 

 and partly by means of sections hardened chiefly in picro-sulphuric acid 

 or Perennyi's fluid and spirit, and stained for the most part with hgema- 

 toxylin, eosin, and safi'ranin, and with borax carmine. 



It has already been stated that examination of the ovary during the 

 spawning season reveals the presence of eggs in various stages of develop- 

 ment. Observers have differed somewhat in the classification of the 

 smaller eggs, but a convenient division of those found in the ovary of a 

 species in which they are pelagic may be stated as follows : — (1) The 

 fully mature, large, free, transparent eggs in which the germinal matter 

 has separated from the deutoplasm and forms a cortical layer enclosing 

 it ; (2) smaller opaque eggs, still contained within the follicle, with a 

 relatively thick egg-membrane, distinct yolk-spherules and germinal vesicle; 

 (3) small transparent eggs which exhibit a conspicuous spherical or ovate 

 nucleus with a mantle of protoplasm, and which are destitute of yolk. 

 This classification does not include the minute ova as they arise from the 

 germ cells, but it comprises all those from the period when they can be 

 distinctly recognised as possessing a nucleus and a protoplasmic layer to 

 the time when they are ready for extrusion and fertilisation. In some 

 species there is no sharp line of demarcation between the second and third 

 stages so far as size is concerned — that is to say, one may trace a pretty 

 regular gradation from the small yolkless eggs to the largest yolked eggs, 

 as in the whiting and gurnard; in most other forms the demarcation 

 between the yolkless and the yolked eggs is marked as maturity is 

 approached. As already indicated, these conditions are associated 

 with the length of the spawning season. 



In dealing with the growth of the intra-ovarian eggs, I shall not 

 deal at any length here with the earlier stages before the deposition 

 of yolk begins. My observations agree on the whole with those 

 of Scharfif^ and, especially, Cunningham. t The smallest eggs were 

 found in the ovary of a haddock (caught on 15th August) along 

 the margin of the lamellae, at their distal ends, or forming digital 

 ingrowths into the stroma. (Plate I., Figs. 1, 2.) In some cases they 

 resembled polynucleated masses, hundreds of minute eggs, measuring from 

 about 0*01 4mm., being crowded together, with an extremely thin layer of 

 protoplasm between. At this stage the nucleus contains numerous small 

 nucleoli, not arranged around the periphery, but scattered irregularly 

 throughout its substance, and subequal in size; a coarse network can 

 also be seen, and some of the nucleoli at least are obviously of the nature 

 of net-knots or karyosomes. In eggs a little larger, ranging about 

 0"035mm., the nucleus is surrounded by a zone of coarsely granular 

 protoplasm which stains very deeply; it contains numerous highly- 

 stained nucleoli, one or more of which may be, but is not always, 



* Quart. Joiirn. Micr.fSci., Vol. xxviii., p. 53. 1888. 

 t Ibid., Vol. xl., p. lOl. 1897. 



G 



